If you look on the Quikrstuff website in FAQ section. The Mach2 rack is rated for two bike maximum config with 2" hitch model RV, 5th wheel, or travel trailer. The rack needs to be inserted into a chassis mounted hitch receiver (not bumper only mount).
What I liked about QuikRstuff Mach2 over the 1UP was the:
- no tools needed to install or adjust for different size (e)bikes (4'11" spouse can install 31lbs hitch rack or 23lbs extra rack, use the optional ramp, and mount/secure her +65lbs Radcity step-thru)
- 120lbs rating per rack (don't need to prep ebike to remove rack bag/battery, adjust handlebars, or seat height to place on rack)
- long rack wheel base to move two ebike side-to-side to fit without touching
- option to use 1 or 2 racks depending on needs (I install one rack, mount my ebike, install second rack in seconds, and mount 2nd ebike)
- no notches on bike tire arms compared to 1UP for a tight and secure clamp on bike tire. (I lock the suspension so the frame doesn't bounce). I drove from Denver to ABQ at 80 mph with zero issues with 4.8" fat tire 95lbs Himiway Cobra Pro ebike (only removed the seatpost for the +7 hour trip home because of several stops along the way).